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Heavy trucks, conspicuity treatment, and the decline of collision risk in darkness

UMTRI-2011-18

In: Journal of Safety Research. Vol. 43, issue 3 (July 2012), p. 157-161.

Authors: John M. Sullivan, Michael J. Flannagan.

Introduction: The influence of amendments to Federal Motor Vehicle Safety Standard (FMVSS) 108, requiring conspicuity treatments on heavy tractors and trailers, was determined in analyses of the odds of fatal collisions in darkness. Method: Comparisons were made between crashes in which conspicuity treatment was likely relevant, and those in which it was likely irrelevant. Results: Over 23 years, the odds that a fatal collision involving a heavy truck occurred in darkness declined by 58% among relevant crashes, while little decline was observed for irrelevant crashes. Disaggregation into crash types revealed the largest declines occurred in fatal rear-end and angle collisions. A parallel analysis of light vehicles also found declines but no differences among crash type. Similar trends were also observed for nonfatal rear end collisions. Conclusion: The results suggest that detection failure may have contributed to the risk of striking a tractor-semitrailer in darkness, and that conspicuity treatments have reduced this risk. Impact on Industry: Conspicuity treatments appear to reduce risk of collision into heavy trucks in darkness. It is likely that this benefit would also extend to other vehicles that are not included in the FMVSS 108 regulation (e.g., buses, single unit trucks, recreational vehicles), although many are so equipped, regardless of the regulation.